Let's talk about the oilfield for a minute. The heart of the oil and gas industry takes place out in the field, where there are a lot of uncertainties. First, all the work is done outdoors, in all types of weather, which means that there is a massive force impacting our work, which we have no control over. Secondly, much of our work is downhole, where we can't see what is happening. Downhole is a harsh environment with high pressure, high temperature, chemicals, scales, and a variety of fluids. Finally, in the oil patch we like to move really fast because, well, there's usually a lot of money on the line. All of this together creates a recipe for unexpected events to derail our plans.
In my time in the oil and gas industry, I've seen all kinds of bizarre, unexpected things happen, some small and some major. In fact, this kind of thing happens so often that you actually come to expect it. You learn to expect the unexpected. Plans rarely go perfectly as planned and thus we should not be surprised when unexpected things happen. Despite this, I'm always amazed when I see projects that are planned so precisely that everything has to go perfectly or else chaos ensues.
What does this mean? Well, it means that our plans should include some margin of error. When you go out to the field, pack some extra tools just in case. If you expect a project to last 5 days, plan for 7. Add a little extra money to your budget just in case. The worst thing that happens is that things go as planned and your margin of error goes "unused". If you do this, I promise you that you'll be a lot less stressed out. You can thank me later.
Remember, it's the oilfield and nothing goes as planned. Plan accordingly.